Molecule
The smallest particle in a chemical element or compound that has the chemical properties of that element or compound, and is composed of two or more atoms held together by chemical bonds.
While an atom is the smallest unit of an element, a molecule is the smallest unit of a compound (or some elements, like O2) that retains its chemical identity.
Word relationships
- Particle: More general; can refer to any tiny piece of matter, not necessarily chemically bonded atoms.
- Unit: More general; refers to a single distinct part of a larger whole.
Commonly confused with
- Atom: An 'atom' is the fundamental unit of an element; a 'molecule' is a group of two or more atoms chemically bonded together.
Word family
- molecular (adjective): Relating to or consisting of molecules.
Collocations
- water molecule
- gas molecule
- organic molecule
- large molecule
- polar molecule
Example sentences
- "A single water molecule consists of two hydrogen atoms and one oxygen atom." Water is a molecule.
- "The intricate structure of a DNA molecule carries the genetic instructions for all known organisms." DNA is a complex molecule.
Memory hook
Think of a 'molecule' as a 'small mass' of atoms, like a tiny 'mole' of material. Small mass
When not to use
Do not confuse 'molecule' with 'atom'; a molecule is typically made of multiple atoms, though some elements exist as single atoms (e.g., noble gases).
Fun facts
- The concept of molecules was first proposed by Amedeo Avogadro in 1811, though it took decades for the scientific community to fully accept it.
- Some molecules, like proteins and DNA, can be incredibly large and complex, containing thousands or even millions of atoms.
Our English vocabulary app: FSRS spaced repetition, 5,000+ curated words across 119 topic groups, CEFR A1 to C2. Explore your mastery with the beautiful Vocabulary World feature.